I'm not sure what grain sizes shoot better ballistically but I'm guessing that 124gr is probably the best choice. And go with +p if the gun can handle it.

Of course this question also begs the question of why are you using 9mm out of a carbine for anything but a range toy (in which case ballistics don't matter)

If you're gonna use a rifle, use a rifle. If you're gonna use a pistol, use a pistol. There's no crossover in real world applications at all in any role for a 9mm semi auto carbine. None. Fantasy meets failed philosophy of use.

Edited by mic6010, 31 August 2016 - 07:58 PM.

"Living in Chicago, it used to be, 'don't go out at night,' or 'be more careful at night'. Now it's turned into a place where it doesn't matter if it's day or night." - John Hendricks.

I'm not sure what grain sizes shoot better ballistically but I'm guessing that 124gr is probably the best choice. And go with +p if the gun can handle it.
Of course this question also begs the question of why are you using 9mm out of a carbine for anything but a range toy (in which case ballistics don't matter)
If you're gonna use a rifle, use a rifle. If you're gonna use a pistol, use a pistol. There's no crossover at all in those roles. None.

Personally, indoors I like the idea of pistol caliber carbine. You get the control and accuracy of a carbine with the recoil, report and flash of a pistol.

My thoughts too, but I am a bit confused on the recoil aspect. Ive been contemplating a 9mm carbine, but read different opinions on the recoil. Many claim it can be harsher due to blowback design, yet others say it is softer.

Personally, indoors I like the idea of pistol caliber carbine. You get the control and accuracy of a carbine with the recoil, report and flash of a pistol.

My thoughts too, but I am a bit confused on the recoil aspect. Ive been contemplating a 9mm carbine, but read different opinions on the recoil. Many claim it can be harsher due to blowback design, yet others say it is softer.

I'm not sure what grain sizes shoot better ballistically but I'm guessing that 124gr is probably the best choice. And go with +p if the gun can handle it.
Of course this question also begs the question of why are you using 9mm out of a carbine for anything but a range toy (in which case ballistics don't matter)
If you're gonna use a rifle, use a rifle. If you're gonna use a pistol, use a pistol. There's no crossover at all in those roles. None.

Yeah but thats a sub machine gun, not a pistol caliber carbine. The MP5 is also a gun thats famously loathed by its users for not having the sufficient stopping power to do the job its made for. Hence the .45 version and hence shorty AR-15s and guns of that category.

But I will give you that in full auto a 9mm sub gun at least makes some sense to use. In semi auto however its just a giant pistol and its still not anywhere near approaching the power of a .233/5.56. There's nobody that is seriously using a 9mm semi auto carbine and there's a reason for that.

They are imo just range toys and nothing more. Either use a pistol for pistol distances or use an SBR in you need to do both. Or even use one of those new fangeld rifle "pistols" with an arm brace before you use a 9mm carbine for anything out side of range use or practice.

Edited by mic6010, 31 August 2016 - 09:08 PM.

"Living in Chicago, it used to be, 'don't go out at night,' or 'be more careful at night'. Now it's turned into a place where it doesn't matter if it's day or night." - John Hendricks.

I'm not sure what grain sizes shoot better ballistically but I'm guessing that 124gr is probably the best choice. And go with +p if the gun can handle it.
Of course this question also begs the question of why are you using 9mm out of a carbine for anything but a range toy (in which case ballistics don't matter)
If you're gonna use a rifle, use a rifle. If you're gonna use a pistol, use a pistol. There's no crossover at all in those roles. None.

Yeah but thats a sub machine gun, not a pistol caliber carbine. The MP5 is also a gun thats famously loathed by its users for not having the sufficient stopping power to do the job its made for. Hence the .45 version and hence shorty AR-15s and guns of that category.

But I will give you that in full auto a 9mm sub gun at least makes some sense to use. In semi auto however its just a giant pistol and its still not anywhere near approaching the power of a .233/5.56. There's nobody that is seriously using a 9mm semi auto carbine and there's a reason for that.

They are imo just range toys and nothing more. Either use a pistol for pistol distances or use an SBR in you need to do both. Or even use one of those new fangeld rifle "pistols" with an arm brace before you use a 9mm carbine for anything out side of range use or practice.

Use good bonded HP loads. Extra velocity from the longer barrel tends to cause more violent expansion.

I like 147s as they are generally subsonic so easier on the noise signature.

If HST bullets were available for reloading, what would probably make an ideal 9mm carbine load would be to take the 125gr bullet from the 357 Sig HST and load it in 9mm cases, from a carbine barrel you should get about the same velocity as 357 Sig so the bullet performance would be correct. It would be cool if Federal would load it that way with a slightly slower powder as a SMG/Carbine load.

Edited by Gamma, 31 August 2016 - 09:36 PM.

Illinois' FCCA is a prime example of the maxim that sufficiently advanced incompetence is indistinguishable from malice.

I think the 147gr gets the most out of the longer barrel, they're barely going fast enough to expand anyway. For most bullet designs, driving the 124gr and lesser weights even faster means they're going to expand more and penetrate less. An exception to this would be the Hornady XTP Critical Duty, Critical Defense / Zombie Max, the petals only expand to a certain extent - usually around .566, and they're not going to expand any more than that so driving them to higher velocities means deeper penetration.

“Most gun control arguments miss the point. If all control boils fundamentally to force, how can one resist aggression without equal force? How can a truly “free” state exist if the individual citizen is enslaved to the forceful will of individual or organized aggressors?

I think the 147gr gets the most out of the longer barrel, they're barely going fast enough to expand anyway. For most bullet designs, driving the 124gr and lesser weights even faster means they're going to expand more and penetrate less. An exception to this would be the Hornady XTP Critical Duty, Critical Defense / Zombie Max, the petals only expand to a certain extent - usually around .566, and they're not going to expand any more than that so driving them to higher velocities means deeper penetration.

With some of those, a high enough velocity would just shear off the petals leaving you with a deeply penetrating wadcutter.

Illinois' FCCA is a prime example of the maxim that sufficiently advanced incompetence is indistinguishable from malice.

Heavier bullets are always "better," all things being equal, because the higher sectional density yields a higher ballistic coefficient and improved penetration. But, when there are caveats, like pistol bullets approaching rifle velocities, you get bullet performance issues.

I'm with Gamma. I think you get the most out of a bonded 147, generally speaking.

Any of the weights will 'function' in a carbine style - my Hoosier Hi Point 995 (it has to live in Indiana as I am in Chicago) happily digests 115 and 124 gr reloads with equal ease and good accuracy. Recoil is mild. Great for dispatching pest varmints.

As to 'benefits' - to start to consider a benefit I'd need to understand the intended purpose. Pistol caliber carbines are great fun plinkers, they are generally easier to shoot more accurately than a handgun, but often have less round capacity. My HP comes with 10 round mags.

Any of the weights will 'function' in a carbine style - my Hoosier Hi Point 995 (it has to live in Indiana as I am in Chicago) happily digests 115 and 124 gr reloads with equal ease and good accuracy. Recoil is mild. Great for dispatching pest varmints.

As to 'benefits' - to start to consider a benefit I'd need to understand the intended purpose. Pistol caliber carbines are great fun plinkers, they are generally easier to shoot more accurately than a handgun, but often have less round capacity. My HP comes with 10 round mags.

All my PCC have the same round count as my pistols, they use the same Glock magazines as my Glocks. So I can use a G26 10 rounder or the 33 rounder or anything in between. I can also use a drum magazine on it that works in the Glocks pistol, but I do not own any of those, so the capacity issue is limited mostly to the Hi Point, yet if memory serves me correctly they have recently increased that capacity with a new magazine.

My understanding is that many of these carbines are modeled after their submachine gun counterparts. When shooting a 9mm submachine gun with a surpressor, 147 grain bullets were commonly used because they are subsonic, i.e. no "crack" when the bullet breaks the sound barrier. If you are shooting something modeled after one of these guns, 147 gr. may cycle more reliably because that's what they were designed for.
As far as velocity, the powder in handgun cartridges is designed to burn more rapidly to maximize its use in a shorter barrel. Rifle powder burns a little slower so that the entire barrel length is used to build velocity. Some have surmised that the extra barrel length may cause more drag and slow down a pistol cartridge because the powder is burnt up before the bullet travels the full length of the barrel.
I know one police chief who tested and confirmed this theory on his department's Marlin Camp 9 carbines years ago. With the same round, he was getting lower velocity through the carbines than through the S&W 59 series pistols. However, other people have tested other ammunition through various carbines and found that this is not always the case.
If it were me, I would find a chronograph and test several rounds through both a pistol and carbine, just to see if you get a gain or loss in velocity.
All things being equal, a 124 grain +P load would be a good place to start.

As far as velocity, the powder in handgun cartridges is designed to burn more rapidly to maximize its use in a shorter barrel. Rifle powder burns a little slower so that the entire barrel length is used to build velocity. Some have surmised that the extra barrel length may cause more drag and slow down a pistol cartridge because the powder is burnt up before the bullet travels the full length of the barrel.

I know one police chief who tested and confirmed this theory on his department's Marlin Camp 9 carbines years ago. With the same round, he was getting lower velocity through the carbines than through the S&W 59 series pistols. However, other people have tested other ammunition through various carbines and found that this is not always the case.

If it were me, I would find a chronograph and test several rounds through both a pistol and carbine, just to see if you get a gain or loss in velocity.

All things being equal, a 124 grain +P load would be a good place to start.

I linked to a site above that actually chronographed several defence rounds through various length barrels. Saves some time and ammo.

While I do plan on building a pistol caliber carbine, it will be with a 7" or shorter barrel. And it would be a toy. I honestly don't understand what purpose a 16" 9mm barrel serves. I see people here saying that they would use hollow points, but you can use hollow point/soft point rifle ammo to more effect compared to a PCC. From what I've read, pistol ammo is far more likely to overpenetrate walls compared to rifle ammo, so it really doesn't make sense to me.

When i still had the 9mm kit for my AUG, I found that 124gr +p hit the sweet spot. it 'felt' the best (subjective evaluation) but also produced marginally better groupings than either 115 gr +p or 147 gr. Offhand at 25 yards, this improvement was in the 1/2" ~ 3/4" range. That's not very significant for a defensive situation, but if accuracy is a question, I found the 124 gr projectile weight to be best. That may vary with other pistol-caliber carbines or loadings. I sold the 9mm kit last year as it was just taking up space in my safe - I hadn't fired it for at least 4 years.

With regards to pistol-caliber carbines or SMGs, my understanding is that most professionals have moved away from those - in general - in favor of a SBR carbine or towards a smaller, unique caliber like FN's 5.7x28 or H&K's 4.6 x 30 due to their ability to defeat simple body armor and remain much more compact than a SBR carbine. I don't know anyone who has fired an MP5 who didn't like it.

While I do plan on building a pistol caliber carbine, it will be with a 7" or shorter barrel. And it would be a toy. I honestly don't understand what purpose a 16" 9mm barrel serves. I see people here saying that they would use hollow points, but you can use hollow point/soft point rifle ammo to more effect compared to a PCC. From what I've read, pistol ammo is far more likely to overpenetrate walls compared to rifle ammo, so it really doesn't make sense to me.

Maybe the reason people use a 16" barrel in a PCC is because they're limited to that barrel size. If short-barreled rifles weren't so heavily regulated, I'm sure most would go with a shorter barrel. As such, it's either a handgun, rifle, or SBR complete with tax stamps, paperwork, and a year's long wait. A shoulder stock on a handgun may help with recoil and handling, but adding a stock without permission makes you a criminal.

While I do plan on building a pistol caliber carbine, it will be with a 7" or shorter barrel. And it would be a toy. I honestly don't understand what purpose a 16" 9mm barrel serves. I see people here saying that they would use hollow points, but you can use hollow point/soft point rifle ammo to more effect compared to a PCC. From what I've read, pistol ammo is far more likely to overpenetrate walls compared to rifle ammo, so it really doesn't make sense to me.

Maybe the reason people use a 16" barrel in a PCC is because they're limited to that barrel size. If short-barreled rifles weren't so heavily regulated, I'm sure most would go with a shorter barrel. As such, it's either a handgun, rifle, or SBR complete with tax stamps, paperwork, and a year's long wait. A shoulder stock on a handgun may help with recoil and handling, but adding a stock without permission makes you a criminal.

I get that. But if someone is going to get a 16" barrel anyway, they you might as well stick with a rifle caliber. The niche that a 16" pistol caliber barrel fits seems really weird.

And while there are regulations on SBRs, it isn't all that heavy anymore. Especially now that CLEO signoff has been eliminated. Just fill out a Form 1 or Form 4 and wait. Sure, there's a $200 tax stamp, but if that's going to break the budget then a niche pistol caliber carbine is probably too extravagant expense in the first place.

Personally, indoors I like the idea of pistol caliber carbine. You get the control and accuracy of a carbine with the recoil, report and flash of a pistol.

My thoughts too, but I am a bit confused on the recoil aspect. Ive been contemplating a 9mm carbine, but read different opinions on the recoil. Many claim it can be harsher due to blowback design, yet others say it is softer.

Recoil is a heck of a lot softer with 9mm in a 10.5" platform. A 10.5" AR shooting 147gr bonded Ranger T's out of a pig fitted barrel has the recoil of a staple gun. The sound signature in a shoothouse is EXTREMELY different than that of a 5.56 with an A2 birdcage. (Which is uncomfortable, even with Peltors). The difference in FLASH signature are ridiculous. With the ranges in that environment, likely in low light, it comes down to what you are better with. My drop on the Rangers is 3.5" at 100 yards consistently...2.5- 3" with 115gr gold dots, and I will take that allllll day.

I dont see the niche for a 16" PCC, but I prefer the shorty for inside work anyway.

Vs.

In here:

I like the 9mm better for indoor work.It has a light on it, and a thordson customs tail end in its current form. I love my rifles, but my most likely confrontation will either be in my home....or on the street with a handgun.

Also,

My wife has no fear whatsoever of the 9mm 10.5....none.... while the cuncussion of the 5.56 is uncomfortable for her.